42 INORGANIC PROXIMATE PRINCIPLES. 



the proportion existing in the solid food, we have found, in common 

 with the results formerly obtained by Barral, that, for a healthy adult 

 man, the average quantity of water introduced into the system is about 

 2000 grammes per day. 



There is every reason to believe that a certain quantity of water also 

 makes its appearance within the body by the liberation of its elements 

 from various organic combinations. This is shown by the fact that a 

 considerable quantity of hydrogen is daily introduced into the system 

 as a constituent element of the organic substances of the food, while 

 only a small part of this quantity reappears, under similar forms of 

 combination, in the excretions. The most reliable estimates, in this 

 respect, are as follows : 



AVERAGE DAILY QUANTITY OF HYDROGEN 



Introduced in organic combinations with the food . . . .40 grammes. 

 Discharged " " " excretions . . .6 



Eesidue unaccounted for 34 " 



Thus not more than fifteen per cent, of the quantity introduced is 

 discharged in the organic ingredients of the excretions. But no hydro- 

 gen is exhaled from the body in a free state, nor in notable quantity in 

 any other form of inorganic combination except water. The surplus 

 must, therefore, pass out as part of the water or watery vapor which is 

 constantly being discharged from various organs. The estimates given 

 above indicate that a little over 300 grammes of water are daily pro- 

 duced in the body in this way. As we shall hereafter see, an important 

 class of the organic ingredients of the food already contain hydrogen 

 and oxygen in the relative quantities necessary to form water; and, 

 when decomposed in the system, may readily yield these elements in the 

 required proportions. 



Furthermore, although it has not yet been proved, in any particular 

 case, that more water is discharged from the system than can be ac- 

 counted for by that introduced, yet a comparison of the average results 

 obtained by different observers, always tends to show a surplus of water 

 in the entire excretions, varying from 200 to 500 grammes over and 

 above that introduced with the food and drink. The quantity of water, 

 however, thus produced in the body is small in comparison with that 

 which is introduced and discharged under its own form. 



While in the interior of the living body, water takes part in the vital 

 functions principally by its physical properties. It is the universal 

 solvent for all the ingredients of the animal fluids, holding them in solu- 

 tion either by its direct liquefying power, or by the aid of other sub- 

 stances which are themselves soluble. It thus enables the nutritious 

 elements of the food to find their way into the circulating fluid, and to 

 penetrate the substance of the solid organs. It permeates the organized 

 membranes of the body and brings into contact with each other the in- 

 organic and organic materials of various parts, and enables them to 



